I'm in the process of gathering parts for my 3-stage Intake Manifold conversion on my 2006 325xi. The last item that I've not been able to find much informaton about has been software.
It looks like you can either go:
1. TMS (Jim-C) $500, gotta send in ECU
2. AA (Karl) $500 gotta send in ECU, visit local AA dealer or buy Simon ($350)
3. Custom Tune.

Now I'm wondering, can our cars (325/328) run 330i OEM tunes? I have access to both a GT1 and Autologic. Both of these can easily program cars at no charge. I'd run a free OEM 330i tune over a $500 custom tune at maybe a 10hp loss any day.
I got my old boss (I used to work at a performance shop) to call up autologic and they said they couldn't flash 330i performance software on my 325i, but my thought is that he hadn't heard of the mod and didn't care to dig into it.

I do own a galletto cable that I know could pull tunes off e46s, though I haven't tried my e90 yet. Maybe it's just the case of pulling a tune off a 330i and uploading it to my 325i.. wouldn't that be sweet

IB4 bricked ecu

I'll try to keep this updated with what I find out, if anybody out there has tuning experience and/or can contribute, please do!

There is lots of tune info is in the 3 stage manifold threads, as well as the AA thread.

it's not as easy as copying 330 software onto your ECM, unfortunately, it doesn't work like that. That's why you need someone like AA to decrypt the files and find the locations of the data that needs to be modified (which varies across computers).

the options are slim, as you listed, though there may be another option when Shiv releases the open flash tablet.

As long as the hardware is the same this should be possible. However, I'm not sure that it will be. My 330xi uses msv70. if you have msv80, flashing my software to your DME will not work. If you have an auto, the transmission software will also probably need to be altered and maybe even DSC. if you physically retrofit a 330i I would be glad to help you with the software bit as I have done a lot of coding and programming.

As long as the hardware is the same this should be possible. However, I'm not sure that it will be. My 330xi uses msv70. if you have msv80, flashing my software to your DME will not work. If you have an auto, the transmission software will also probably need to be altered and maybe even DSC. if you physically retrofit a 330i I would be glad to help you with the software bit as I have done a lot of coding and programming.

Do you know if it's only the "tune" (air/fuel/timing) parameters which change between 325 and 330 or does the entire software architecture change? I did hear that on e46s the location of relevant data changes between ecus